Micro-blogging company Twitter has been hit with a patent infringement lawsuit by a mass notification and emergency alert systems provider in the United States.

An attorney for TechRadium said that Twitter had designed its system in a way that violates three of the plaintiff's patents.

"The problem is the Twitter architecture. The way they have it set up is technology that is squarely within TechRadium's patents," said Shawn Staples, an attorney with Mostyn Law, in a phone interview on Wednesday.

Consequently, organisations could use Twitter to do the type of mass notification that TechRadium provides via its IRIS (Immediate Response Information System) technology.

"There have been recently some municipalities and other organisations who have claimed they'll use Twitter for emergency notification systems, and that's technology that TechRadium has spent many years and a lot of money developing," Staples said.

IRIS lets organisations broadcast a single message to multiple recipients who can receive it on a variety of devices like regular phones, cell phones and fax machines. It's intended to quickly alert people about emergency situations.

The lawsuit, filed on Tuesday in the US District Court for the Southern District of Texas, Houston Division, seeks among other things unspecified damages, recovery of attorneys' fees and a permanent injunction against Twitter.

The patents Twitter is allegedly infringing are patent number 7,130,389, granted in October 2006 for a "digital notification and response system"; patent number 7,496,183, granted in February 2009 for a "method for providing digital notification"; and patent number 7,519,165, granted in April 2009 for a "method for providing digital notification and receiving responses."

Twitter didn't immediately respond to a request for comment.